-# Create a const field of the given field class.
-#
-# The field is part of a dummy stream, itself part of a dummy trace created
-# from trace class `tc`.
-
-
-def _create_const_field(tc, field_class, field_value_setter_fn):
- field_name = 'const field'
-
- class MyIter(bt2._UserMessageIterator):
- def __init__(self, config, self_port_output):
- nonlocal field_class
- nonlocal field_value_setter_fn
- stream = _create_stream(tc, [(field_name, field_class)])
- packet = stream.create_packet()
-
- field_value_setter_fn(packet.context_field[field_name])
-
- self._msgs = [
- self._create_stream_beginning_message(stream),
- self._create_packet_beginning_message(packet),
- ]
-
- def __next__(self):
- if len(self._msgs) == 0:
- raise StopIteration
-
- return self._msgs.pop(0)
-
- class MySrc(bt2._UserSourceComponent, message_iterator_class=MyIter):
- def __init__(self, config, params, obj):
- self._add_output_port('out', params)
-
- graph = bt2.Graph()
- src_comp = graph.add_component(MySrc, 'my_source', None)
- msg_iter = TestOutputPortMessageIterator(graph, src_comp.output_ports['out'])
-
- # Ignore first message, stream beginning
- _ = next(msg_iter)
- packet_beg_msg = next(msg_iter)
-
- return packet_beg_msg.packet.context_field[field_name]
-
-